Film wrapped packages of foodstuffs such as sliced bacon, ham slices, luncheon meats and the like conventionally utilize a semi-rigid supporting member or backing board on which the typically greasy product is situated within the outer film wrap.
In the packaging of sliced bacon in particular, a widely used technique is to provide a semi-rigid paperboard or fibrous backing board support having a wax or polyolefin resin coating, such as polyethylene, on which a plurality of bacon slices are arranged in edge overlapping or shingled relation. The shingle of bacon is then overwrapped with a transparent packaging film, which is typically evacuated and sealed to or around the backing board. The backing board may be of an L-type which has a perforated score line along one side of the main support portion of the board. The score line defines a flap which is folded over to cover an end portion of the bacon shingle on the backing board such that the lean edge portions of the slices are predominantly displayed for viewing through the transparent overwrap. Such a display of lean edges of the bacon strips in the package makes the product more attractive and consequently more merchantable. A window is ordinarily formed in the main portion of the backing board so that at least a portion of both sides of a bacon slice is visible for customer inspection to fulfill certain government regulations.
Although coated paperboard backing boards have achieved wide acceptance in the industry, there is a tendency for the paperboard to absorb moisture through wicking which occurs from a transfer of water from the moist package product to the backing board. Wicking is a particular problem around the cut perimeter of the backing board, the exposed edges of any windows or openings cut in the backing board, and along the perforations of the score line defining the flap portion. The paperboard backing board can become relatively limp and even warped due to this wicking, and can further become discolored or stained, detracting from the appearance and saleability of the bacon. Limp or warped packages are of course more difficult to handle.
In an effort to avoid the wicking problem which occurs around the window aperture cut in the paperboard, coated paperboard backing boards have been made having a transparent plastic window adhered to the backing board covering the window aperture from the rearward side and adjacent the bacon. It has been found that this back window cover can become unsecured or detached from the coated surface of the backing board thereby defeating its usefulness. Applying the window further requires an additional step in the manufacture of the paperboard backing board, and increases the cost of the finished board.
The other type of backing board commonly used in the marketplace for packaging sliced bacon utilizes a plastic member, which may be of a laminate construction, of a polymeric sheet material. Such material is insensitive to grease and moisture, thus surmounting one of the major problems of the coated paperboard backing board insert.
A transparent polyolefin resin, such as polyethylene, typically forms the base layer for this type of backing board. One or both sides of the base layer will be printed over substantially the entire surface. A certain portion of the base layer is left entirely unprinted to serve as a transparent window area for viewing the bacon. It will be noted that it is generally desired that the portion of the bacon which is not required to be exposed by virtue of packaging regulations should be protected from the deliterious affect of light. For this, as well as merchandising reasons, a large portion of the backing board surface is generally required to be opaque.
One widely used plastic backing board is of a single ply and bears opacifying printing and decoration only on the side which faces away from the bacon shingle. No overcoating of covering material is provided on this printed side to "trap in" the printing. It is an F.D.A. regulation that any printing on a backing board must have a barrier between it and any contained food products such that direct contact cannot occur between the food product and the printing. Although the uncoated printing is spaced from the bacon by the single ply base sheet, the possibility nevertheless exists that direct contact between the bacon and the printing can occur if the bacon wraps around the board in the course of packaging. For this reason, such backing boards with uncoated printing have not achieved widespread acceptance in the industry.
Yet another plastic backing board is a laminate having a transparent core or base layer of polystyrene which is printed on each side with an ink coverage that is complete except in the clear window area. A polyethylene or varnish overcoat is then provided covering the entire printed backing board surface, including the window area, thereby trapping in the printing. Printing on both sides for decorating and opacifying the overall backing board area is asserted to be necessary in this backing board to avoid the tendency of the polystyrene base layer to develop a curl caused by film shrinkage induced by the drying ink. Such curling can cause sealing problems in the packaging, known as leakers, as well as difficulties in handling of the backing boards on conventional high speed bacon packaging machinery. It will be recognized that printing on both sides of the backing board can increase the amount of ink used, compared to printing only on one side, and also requires an overcoat layer on both sides of the board to trap in the printing.
A general consideration for all bacon backing boards is that they be rigid enough to fulfill their support function and permit easy handling by bacon packaging machinery, that they receive printing readily to form an attractive package, and that they be inexpensive to produce. It is also desirable that the insert be relatively soft and flexible in order to promote better vacuum packaging of the bacon shingle and avoid the problem of leakers. Such leakers can be caused by a bacon board insert which fails to stay confined within the vacuum cavity during vacuum packing, moving into the sealing area such that a total seal is not accomplished and the vacuum is ultimately lost or leaked away. In this regard, it is speculated that the relatively inflexible coated paperboard backing board is more prone to forming such leakers than a more pliant plastic board. Leakers can also be caused by punctures to the overwrap itself from burrs or slivers remaining from the die-cutting and perforation steps in manufacture of the L-type bacon backing boards. Leakers are a significant problem in the industry, and a leaker rate of 1% or less is considered very desirable.